JP2022070164A - Reflection suppression foam sheet - Google Patents

Abstract

To provide a novel reflection suppression member capable of being manufactured without going through a complicated manufacturing step, having a low reflectivity, and having good appearance.SOLUTION: A reflection suppressing foam sheet is obtained by foaming and curing an emulsion composition containing a resin component and a black colorant. The black colorant contains a dye (A) and a pigment (B). The solid content of the black colorant in the emulsion composition is 5 to 15 mass%. The solid content ratio ((A)/(B)) between the dye (A) and the pigment (B) is 0.01 to 0.35.SELECTED DRAWING: None

Description

The present invention relates to an antireflection foam sheet.

In the field of optical equipment and the like, a material (reflection suppressing member) capable of reducing the reflection of light incident on the device is being developed.

For example, in Patent Document 1, a skeleton portion of urethane foam and a black layer are provided, the skeleton portion forms a hollow portion composed of communicating bubbles, and the black layer is formed on the surface of the skeleton portion. A light-shielding material for cameras, wherein the black layer comprises a paint containing at least one black pigment selected from the group consisting of graphite and carbon black and a binder, and the black layer has a thickness of 1 to 25 μm. Is disclosed. According to the light-shielding material according to Patent Document 1, it is possible to obtain a light-shielding material for a camera that exhibits excellent light-shielding performance.

Further, in Patent Document 2, as the antireflection layer, (A) non-aggregating resin fine particles having an average particle size of 15 to 30 μm, (B) aggregated resin fine particles having an average particle size of 15 to 30 μm, and (C) are formed in a synthetic resin matrix. It contains carbon black fine particles with an average particle size of 1 μm or less, and the blending ratio of the component (A) and the component (B) is 10: 1 to 1: 2 by weight, and the blending amount of the component (C) is (A). An antireflection film in the range of 3 to 50% by weight based on the total weight of the component (B) and the component (B) is disclosed. According to the antireflection film according to Patent Document 2, the film has an excellent antireflection effect and is thin, so that it is possible to suppress the generation of dust.

Japanese Unexamined Patent Publication No. 2001-109108 Patent No. 3902827

Since the light-shielding material according to Patent Document 1 is mainly manufactured through the following three manufacturing steps, it has a drawback that the manufacturing process is complicated.
1) Step of manufacturing polyurethane foam as a base material 2) Step of cutting the manufactured polyurethane foam to a predetermined thickness 3) Step of impregnating a paint composed of a black pigment and a binder Further, the light-shielding material according to Patent Document 1 has a thickness. There is also the drawback that it is difficult to change. Specifically, if the thickness is changed by slicing after the impregnation of the paint is completed, the skeleton cross section of the polyurethane foam is not impregnated with the paint, so that the blackness is low and the performance such as light shielding property and reflection suppression is deteriorated. In some cases. Therefore, a reflection inhibitor that is stable and has an excellent blackness is desired.

Further, when manufacturing the reflection suppressing member according to Patent Document 2, by adding spherical non-aggregating / cohesive resin fine particles to the aqueous synthetic resin matrix (emulsion), the water content of the compounding system is vaporized and dried. The coating film is thinned by allowing the coating film to be exposed, and spherical fine particles are exposed on the surface of the coating film. However, with this method, the film thickness cannot be increased in order to dry the coating film. Further, the reflection suppressing member according to Patent Document 2 does not contribute to the reflectance except that the surface has a predetermined shape and contains a black colorant. That is, there is no element that can reduce the reflectance other than the surface of the coating film. Therefore, further reduction in reflectance cannot be expected, and the reduction in reflectance may be insufficient.

In addition, if proper foaming is difficult in the manufacturing process, the fine bubble structure may be destroyed. As a result, voids (for example, a region where there is no foam layer and the PET film as a carrier is exposed) may be generated on the sheet surface, or the size of the void portion on the surface of the foam layer may become large. Since such voids and voids can be a factor of deteriorating the optical characteristics, the appearance may be important in the reflection suppressing member.

Therefore, it is an object of the present invention to provide a novel reflection suppressing member which can be manufactured without going through a complicated manufacturing process, has a low reflectance, and is excellent in appearance.

The present inventors have conducted diligent research and found that the above-mentioned problems can be solved by using a predetermined foamed sheet, and have completed the present invention. That is, the present invention is as follows.

The present invention
A reflection-suppressing foamed sheet obtained by foaming and curing an emulsion composition containing a resin component and a black colorant.
The black colorant contains a dye (A) and a pigment (B).
The solid content of the black colorant in the emulsion composition is 5 to 15% by mass.
It is a reflection-suppressing foamed sheet characterized in that the solid content ratio ((A) / (B)) of the dye (A) and the pigment (B) is 0.01 to 0.35.

The density may be 50 to 500 kg / m ³ .
The degree of blackness (L * value) may be 22 or less.
The dye (A) may be a metal complex salt dye or an azo dye, and the pigment (B) may be carbon black having a particle size of 300 nm or less.
The specular reflectance of 60 ° incident light in light having a wavelength of 300 to 800 nm may be 0.2% or less, and the thickness may be 80 to 1200 μm.
The saturation indicated by the distance [√ (a * value ^ 2 + b * value ^ 2)] from the intersection of the a * value and b * value coordinates (a * value, b * value: 0,0) is 1.5 or less. May be.

According to the present invention, it is an object of the present invention to provide a novel reflection suppressing member which can be manufactured without going through a complicated manufacturing process, has a low reflectance, and is excellent in appearance.

If isomers are present in the described compounds, all possible isomers can be used in the present invention unless otherwise noted.

Hereinafter, the raw material, structure / physical properties / properties, and uses of the reflection-suppressing foamed sheet (hereinafter, may be simply referred to as “foamed sheet”) according to the present invention will be described.

<<< Raw materials >>
The foamed sheet is obtained by foaming and curing the emulsion composition. The emulsion composition contains a resin component, a black colorant, and a dispersion medium. The emulsion composition preferably contains spherical fine particles (solid fine particles). The emulsion composition may contain other components.

Here, the non-volatile component (component excluding the dispersion medium) contained in the emulsion composition is usually the solid content of the foamed sheet. Therefore, in the following description, the non-volatile content contained in the emulsion composition and the solid content contained in the foamed sheet will be described without particular distinction.

If the emulsion composition contains reactive components, the foamed sheet may contain reaction products of those reactive components.

<< Resin component >>
The resin component may be a conventionally known one that can be used as a reflection inhibitor, and is not particularly limited, but is limited to acrylic resin, vinyl ester resin, silicone resin, urethane resin, epoxy resin, and vinyl chloride. Examples thereof include based resins and fluororesins. Only one type of these may be used, or two or more types may be used in combination.

The resin component may be a homopolymer or a copolymer.

The resin component preferably contains an acrylic resin, a vinyl ester resin, a silicone resin, and a urethane resin. Further, the resin component may contain other resins (for example, EVA and the like). Further, the resin component preferably contains an acrylic resin and a vinyl ester resin and / or a silicone resin.

The acrylic monomer constituting the acrylic resin is not particularly limited, but is an acrylic acid ester such as methyl acrylate, ethyl acrylate and n-butyl acrylate; methyl methacrylate, ethyl methacrylate and n-methacrylic acid. Methacrylic acid esters such as butyl; acrylic acid; methacrylic acid; and the like. Only one type of these may be used, or two or more types may be used in combination.

Examples of the vinyl ester-based monomer constituting the vinyl ester-based resin include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl laurate, vinyl versatic acid and the like. Only one type of these may be used, or two or more types may be used in combination.

The vinyl ester-based monomer preferably contains a versatic acid vinyl ester. That is, the vinyl ester-based resin is preferably a homopolymer or a copolymer of a versatic acid vinyl ester (for example, a copolymer of a versatic acid vinyl ester and an acrylic monomer).

The silicone-based resin is not particularly limited as long as it contains a silane compound as a raw material monomer, and is not particularly limited, and is dimethyl silicone, methylphenyl silicone, various modified silicones (for example, amino-modified silicone, epoxy-modified silicone, polyether-modified silicone emulsion, alkyl-modified silicone emulsion). , Fluorine-modified silicone, etc.) can be used. The silicone-based resin may be a copolymer such as a silicone acrylic copolymer.

In the emulsion composition, the resin component as described above exists as a resin emulsion, that is, as resin particles dispersed in a dispersion medium. Such resin particles can have a particle size of, for example, 1.0 μm or less, more preferably 0.5 μm or less, still more preferably 0.2 μm or less. The particle size of the resin particles can be measured by, for example, a laser microscope by a laser diffraction / scattering method.

The emulsion can be produced, for example, by blending a raw material monomer of a resin component in an aqueous medium and emulsion-polymerizing the raw material monomer in the presence of various additives such as an emulsifier and a polymerization initiator.

The pH of the emulsion may be appropriately adjusted according to the type of resin, additive components, etc., but may be 4 to 12, 5 to 10, or the like.

The ratio (solid content concentration) of the total resin component in the foamed sheet or the emulsion composition is 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95. It can be mass% or more.

<< Black Colorant >>
The black colorant contains a dye (A) and a pigment (B).

As the dye (A), a commonly used black dye can be used, but it is desirable that the dye (A) is soluble in water and has a high pH. If the pH is less than 6.0, the pH may be adjusted to 6.0 or more in advance and then added to the emulsion composition. The dye (A) preferably contains one or more selected from metal complex salt dyes and azo dyes.

As the pigment (B), a commonly used black pigment (for example, a carbon-based pigment) can be used, but carbon black can be preferably used. The carbon black preferably has a particle size of 300 nm or less. By setting the particle size of carbon black in such a range, it is possible to suppress a decrease in the concentration of carbon black per volume after foaming, and a large number of carbon particles are uniformly dispersed, resulting in a difference in shade of black. It becomes difficult and excellent color development is obtained. Here, when carbon black having a small average particle size is used in a normal reflective member, it does not contribute to the unevenness of the surface of the reflective member, so that it becomes glossy and the reflectance can be improved. On the other hand, when the reflective member is a foam, the bubbles existing on the surface reduce the generation of such luster, so that the adverse effect of using carbon black having a small average particle size can be suppressed.

Here, the black colorant can be, for example, the following.
Nikazol RX-3002L (pH 9, solid content concentration 35%) manufactured by Nippon Carbide Industry Co., Ltd. was prepared by adding a black colorant (target component) so that the solid content concentration was 2 wt%, and molded into a sheet. do. If the thickness of the sheet is less than 200 μm, stack it so that the total thickness is 200 μm or more, measure L * using the color difference meter CR-400 manufactured by Konica Minolta Japan Co., Ltd., and the value of L * is 30 or less. The thing is a black colorant.

The solid content (solid content concentration) of the black colorant (or the total of the dye (A) and the pigment (B)) in the foamed sheet (or in the emulsion composition) is 5 to 15 mass by mass. %, Preferably 6 to 14% by mass or 7 to 12% by mass.

The solid content ratio ((A) / (B)) of the dye (A) and the pigment (B) in the foamed sheet (or in the emulsion composition) is 0.01 to 0.35. , 0.03 to 0.34 or 0.05 to 0.20.

<< Dispersion medium >>
The aqueous medium used as the dispersion medium of the emulsion composition contains water as an essential component, but may be a mixture of water and a water-soluble solvent. The water-soluble solvent is, for example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl carbitol, ethyl cellosolve, butyl cellosolve, polar solvents such as N-methylpyrrolidone, and one or more of these. A mixture of the above may be used.

<< Spherical fine particles >>
Spherical fine particles are resin fine particles having a shape close to a true sphere. As the spherical fine particles, for example, it is preferable that the diameter of any fine particle is measured at 5 points by SEM and the ratio (maximum diameter / minimum diameter) of the maximum diameter to the minimum diameter is 1.5 or less.

The foamed sheet has recesses derived from pores and convex portions derived from spherical fine particles on its surface. Further, convex portions derived from spherical fine particles are also formed on the inner wall portion of the pores (communication holes). Further, since the foamed sheet has a large surface area, the region of the convex portion formed by the spherical fine particles also increases. Such recesses and protrusions effectively reduce the reflectance of light.

The particle size of the spherical fine particles is preferably 2 to 150 μm, 2 to 125 μm, or 3 to 100 μm. By setting the particle size of the spherical fine particles in such a range, the above-mentioned effect derived from the spherical fine particles can be enhanced.

Ten spherical fine particles are selected from the SEM image, the diameters of each of the five spherical fine particles are measured, and the average value of the maximum diameters of each spherical fine particle is taken as the particle size of the spherical fine particles.

The structure of the spherical fine particles can be a known structure such as a hollow (balloon) shape, a solid shape, or a bead shape.

The material constituting the spherical fine particles is not particularly specified, but an acrylic copolymer, a silicone-based resin, or the like may be used as a commonly used resin material.

The spherical fine particles may be colored (for example, colored black) by applying a fine inorganic filler or a colorant such as carbon black to the surface thereof.

As the spherical fine particles, two or more kinds of spherical fine particles having different particle diameters, structures or materials may be used in combination.

The content (solid content concentration) of the spherical fine particles in the foamed sheet or the emulsion composition is preferably 5 to 30% by mass or 5 to 25% by mass. By setting the content of the spherical fine particles in such a range, the appearance of irregularities derived from the spherical fine particles becomes appropriate, the effect of reducing the reflectance is improved, and the spherical fine particles can be prevented from falling off from the foamed sheet. can.

<< Other ingredients >>
The emulsion composition may contain, as other components, a cross-linking agent (curing agent), a foaming agent / bubble stabilizer, a surfactant, a viscosity modifier, an emulsifier, a diluent, a water-soluble polymer and the like. Further, the emulsion composition may contain various components (polymerization initiator, surfactant, emulsifier, protective agent, etc.) used in producing the emulsion as they are. Further, in order to complement the black color and make it achromatic, a colored colorant other than black color (for example, a dye or a pigment) may be contained.

Examples of the cross-linking agent include an epoxy-based cross-linking agent, a melamine-based cross-linking agent, an isocyanate-based cross-linking agent (for example, an aliphatic isocyanate), a carbodiimide-based cross-linking agent (either an emulsion or a water-soluble type), and an oxazoline-based cross-linking agent. A cross-linking agent (either an emulsion or a water-soluble type may be used) or the like can be used.

The content of the cross-linking agent may be adjusted appropriately according to the type of functional group contained in the resin to be used, the amount of the functional group, and the like.

Examples of the cross-linking method using a curing agent include physical cross-linking, ionic cross-linking, and chemical cross-linking, and the cross-linking method can be selected according to the type of resin.

The foaming agent / bubble stabilizer is a substance that can improve the foaming property, make the bubbles finer / homogenized, and stabilize the generated bubbles (extend the life) when the bubbles are generated in the emulsion composition. Is.

Examples of the foaming agent / bubble stabilizer include anionic surfactants such as sodium dialkyl sulfosuccinate and ammonium stearate, amphoteric ion surfactants such as alkyl betaine and alkylamine oxide, fatty acid alkaminoamides, ethers and esters. Examples include non-ionic surfactants. These may be used alone or in combination of two or more.

<<< Structure / Physical Properties / Properties of Foam Sheet >>>
The foam sheet has an open cell structure. Not all bubbles need to have an open cell structure, and some of them may have a closed cell structure.

The area of the sheet and the like can be changed as appropriate according to the application.

<< Thickness >>
The thickness of the foam sheet is preferably 80 to 1200 μm, more preferably 100 to 500 μm. With such a sheet thickness, the light absorption effect derived from each component becomes appropriate, and the effect of reducing the reflectance is improved.

<< Density >>
The density of the foamed sheet (foamed layer) is preferably 50 to 500 kg / m ³ , more preferably 50 to 400 kg / m ³ , and even more preferably 50 to 250 kg / m ³ .

The density is an apparent density obtained by dividing the weight of the sheet (foamed layer) by the thickness and area of the sheet (foamed layer) in accordance with JIS K 6401.

<< Reflectance >>
The foam sheet has a reflectance of 0.2% or less, more preferably 0.15% or less, still more preferably 0.12% or less, and 0.09. The following is particularly preferable.

The reflectance is measured with an ultraviolet / visible spectrophotometer (UV-3100PC, Shimadzu Corporation) at an incident angle of 60 ° and a polarizing element angle of 45 ° in the region of 300-800 nm, and the average reflectance is used. It was obtained. The measurement is performed in an environment where the room temperature is 23 ± 2 ° C. and the humidity is 50 ± 5%. The test piece shall be tested in an environment of room temperature 23 ± 2 ° C. and humidity 50 ± 5% for 24 hours or more.

<< Blackness (L * value) >>
The foamed sheet preferably has a blackness (L * value) of 22 or less, more preferably 21 or less, and even more preferably 20 or less. The degree of blackness (L * value) can be measured using a color difference meter (CR-400 manufactured by Konica Minolta Japan Co., Ltd.).

<< Saturation >>
The foam sheet has the saturation indicated by the distance [√ (a * value ^ 2 + b * value ^ 2)] from the intersection of the a * value and b * value coordinates (a * value, b * value: 0,0). , 1.5 or less, more preferably 1.3 or less, and particularly preferably 1.0 or less. The a * value and the b * value can be measured using a color difference meter (CR-400 manufactured by Konica Minolta Japan Co., Ltd.). The saturation can be adjusted by blending a coloring component (for example, a blue pigment) that is a complementary color of the dye (A) and the pigment (B). By setting the saturation in such a range, the optical characteristics required for the present invention can be further improved.

According to the present invention, two layers having different coloring sites (by setting the blending ratio of the dye and the pigment in a predetermined range and the content of the black colorant in a predetermined amount) for the dye and the pigment ( It is considered that the resin layer dyed with the dye and the pigment layer covering the resin surface layer) are formed in the foam in a well-balanced manner and have a high degree of blackness. Further, when the blending ratio of the dye and the pigment is within a predetermined range, the color tone derived from the dye and the color tone derived from the pigment are averaged, and the effect of increasing the blackness can be achieved. According to the present invention, in the case of a foam having high foaming and a high degree of blackness, the light absorption rate is high, and the void ratio on the surface of the foam is high due to the high foaming. It is very useful as a reflection inhibitor because it can reduce the reflection due to the difference in the refractive index of. Further, according to the present invention, since the appearance is excellent (the generation of voids, cracks and the like is suppressed), such an effect can be stably exhibited.

<<< Manufacturing method of foam sheet >>>
The foamed sheet is obtained by foaming / curing the emulsion composition.

Hereinafter, an example of a method for producing an emulsion composition will be described, but each step may be carried out continuously or dividedly within a range that does not impair the effect of the present invention, and each step may be carried out in a plurality of steps. It may be carried out multiple times, or a plurality of steps may be carried out at the same time.

<< Preparation process >>
In the preparation step, an emulsion composition which is a raw material mixture of foams is prepared by mixing each of the above-mentioned raw materials. The mixing method is not particularly limited, but for example, mixing may be performed while stirring in a container such as a mixing tank in which each component is mixed.

<< Foaming / curing process >>
In the foaming / curing step, a predetermined foaming gas is added to the emulsion composition obtained in the preparation step, and these are sufficiently mixed to allow a large number of bubbles to exist in the emulsion composition (foaming emulsion composition). To. This foaming / curing step is usually carried out by sufficiently mixing the raw material mixture of the liquid foamed sheet obtained in the raw material preparation step with the foaming gas by a mixing device such as a mixing head.

<Gas for foaming>
The foaming gas mixed in the emulsion composition in the stirring / foaming step forms bubbles (cells) in the foam, and the foaming ratio and density of the obtained foam are determined by the amount of the foaming gas mixed. Is decided. In order to adjust the density of the foamed sheet, the required foamed sheet density is determined from the desired foamed sheet density and the volume of the foamed sheet raw material (for example, the internal volume of the mold into which the foamed sheet raw material is injected). The weight of the raw material may be calculated, and the amount of the foaming gas may be determined so as to have a desired volume at this weight. Air is mainly used as the type of gas for foaming, but an inert gas such as nitrogen, carbon dioxide, helium, or argon can also be used.

<foaming method / foaming conditions>
As the foaming method used in the foam preparation method according to the present invention, a mechanical floss (mechanical floss) method is used. The mechanical floss method is a method in which air in the atmosphere is mixed with the emulsion composition and foamed by stirring the emulsion composition with a stirring blade or the like.

As the stirring device, a stirring device generally used in the mechanical floss method can be used without particular limitation, and for example, a homogenizer, a dissolver, a mechanical floss foaming machine and the like can be used. According to this mechanical floss method, by adjusting the mixing ratio of the emulsion composition and air, a foamed sheet having a density suitable for various uses can be obtained.

Although it is possible to use other foaming methods in combination as the foaming method, it is not preferable to use the foaming method using a chemical foaming agent in combination because the ratio of open cells is low and the reflectance is easily improved.

The mixing time of the emulsion composition and air is not particularly limited, but is usually 1 to 10 minutes, preferably 2 to 6 minutes.

The mixing temperature is not particularly limited, but is usually normal temperature.

The stirring speed in the mixing is preferably 200 rpm or more (more preferably 500 rpm or more) in order to make the bubbles finer, and preferably 2000 rpm or less (more preferably 800 rpm or less) in order to smooth the discharge of the foam from the foaming machine.

As described above, a foamed emulsion composition (foamed emulsion composition) is obtained.

<Formation of foam>
The foamed emulsion composition is formed into a foam such as a sheet having a desired thickness by a known means such as a doctor knife and a doctor roll.

<Curing>
As a method for curing the foam, a known method can be used. The foam according to this embodiment can be self-crosslinked, but the foam may be cured by applying energy to crosslink the resin constituting the emulsion via a crosslinking agent.

The step of applying energy is not particularly limited, and examples thereof include a heating step (thermal cross-linking).

In the heating step, the dispersion medium in the foamed emulsion composition is evaporated. The drying method at this time is not particularly limited, but for example, hot air drying or the like may be used. Further, the drying temperature and the drying time are not particularly limited, but may be, for example, about 1 to 3 hours at about 80 ° C.

Further, in this heating step, the dispersion medium evaporates from the foamed emulsion composition, and the path when the vapor escapes is communicated from the inside to the outside of the foamed sheet. Therefore, in the foam according to the present embodiment, since the path when the water vapor escapes remains as open cells, at least a part of the bubbles existing in the foam sheet becomes open cells.

Here, when the foaming gas mixed in the stirring / foaming step remains as it is, it becomes closed cells in the obtained foaming sheet, and when the mixed foaming gas escapes steam in this step. When it is communicated with, it becomes open cells in the obtained foamed sheet.

When a cross-linking agent is added, the heating step proceeds and completes the cross-linking (curing) reaction of the raw material. Specifically, the raw materials are crosslinked with each other by the above-mentioned cross-linking agent to form a cured foam sheet.

The heating means at this time is not particularly limited as long as the raw material can be sufficiently heated and the raw material can be crosslinked (cured), but for example, a tunnel type heating furnace or the like can be used.

Further, the heating temperature and heating time may be any temperature and time as long as the raw material can be crosslinked (cured), and may be, for example, about 1 hour at 80 to 150 ° C. (particularly about 120 ° C.). ..

<<< Other layers >>>
The foamed sheet may have a layer (other layer) other than the foamed layer. Examples of the other layer include a base material. The base material is used, for example, for casting the foam composition when molding the foam layer into a sheet, and is integrated with the foam layer. As such a base material, for example, a base material sheet that is difficult for the emulsion composition to permeate and has low elasticity may be used. Specific examples of the base material include PET sheets. In addition, such a base material is a treatment that does not impair the performance required for the base material (inhibition of penetration of emulsion composition, elasticity, etc.) such as those that have been mold-released, sand mats, and chemical mat treatments. May be done. Further, as the base material, an adhesive tape, a non-woven fabric, a woven fabric or the like may be used. When the foamed sheet is a laminate having a foamed layer and other layers, a foamed layer may be formed on the foamed layer using the other layer as a base material, or the foamed layer and the other layer may be manufactured separately to form an adhesive or the like. It can be manufactured by a method such as joining these layers to each other.

<<< Applications of foam sheet >>>
Since the foam sheet is excellent in the effect of reducing the reflectance, it can be applied to various optical instruments. For example, in an optical instrument, it can be used as an interior member constituting a path between an optical element and an opening in which light is incident / emitted. More specifically, it can be used as a member to be attached to the inside of a lens hood such as a gasket around a light source such as an LED or an optical sensor (for example, a stereo camera (camera sensor)).

<<< Preparation of foam sheet >>>
<< Raw materials >>
<Emulsion>
(Material for matrix resin 1)
Acrylic Styrene Copolymer Emulsion pH 8.0
Solid content 50%
(Material for matrix resin 2)
Acrylonitrile-Acrylic Acid Alkyl Ester-Itaconic Acid Copolymer Emulsion pH 9.0
Solid content 60%
(Material for matrix resin 3)
Polyether carbonate urethane emulsion pH 8.0
Solid content 60%
(Material for matrix resin 4)
Silicone / Acrylic Copolymer Emulsion pH 6.0
Solid content 45%
(Material 5 for matrix resin)
Versatic Acid Vinyl Ester Copolymerized Acrylic Emulsion pH 8.0
Solid content 60%
<Foaming agent>
(Anionic Surfactant 1)
Ammonium stearate pH11
Solid content 30%
(Anionic Surfactant 2)
Sodium alkyl sulfosuccinate pH 9.3
Solid content 35%
(Amphoteric surfactant 1)
Coconut oil fatty acid amide propyl betaine pH 7.5
Solid content 30%
(Amphoteric surfactant 2)
Millistyl Betaine pH 6.5
Solid content 36%
(Nonion Surfactant 1)
Polyoxyethylene alkyl ether pH 6.5
Solid content 50%
<Crosslinking agent>
(Crosslinking agent 1)
Polyisocyanate Number of functional groups: 3.5
<Spherical fine particles>
(Spherical fine particles 1)
Particle size: 20 μm
White methacrylic acid beads (not hollow)
(Spherical fine particles 2)
Particle size: 30 μm
White silicone beads (not hollow)
(Spherical fine particles 3)
Particle size: 100 μm
White methacrylic acid beads (not hollow)
(Spherical fine particles 4)
Particle size: 3 μm
White silicone beads (not hollow)
<Black colorant>
(Black colorant 1)
Carbon black aqueous dispersion Carbon concentration: 30 wt%
Carbon particle size: 138 nm
(Black colorant 2)
Conductive carbon water dispersion Carbon concentration: 25 wt%
Carbon particle size: 88 nm
(Black colorant 3)
Black dye Dye concentration: 25 wt%
Metal complex salt dye (black colorant 4)
Black dye Dye concentration: 25 wt%
Azo acid dye (blue colorant)
Blue pigment aqueous dispersion (ingredient: copper phthalocyanine)
Pigment concentration: 33 wt%
<Base material>
Plain PET film

<< Raw material preparation / foaming / curing >>
Emulsion compositions were prepared by mixing the components shown in Table 1 as raw materials for foams according to Examples, Comparative Examples and Reference Examples.
An inert gas such as air or nitrogen gas was added to each emulsion composition and foamed by a mechanical floss method to obtain an foamed emulsion composition (foaming condition: 100 to 1000 rpm).
After casting the effervescent emulsion composition on the PET release liner, heat treatment (oven or drying oven) was performed to obtain effervescent sheets according to Examples, Comparative Examples and Reference Examples.

The density of each foam sheet is shown in each table.
The density of the foam sheet was measured according to the method described above.
The density of the foamed sheet was adjusted by changing the injection amount of the inert gas such as air or nitrogen gas.

The thickness of the foam sheet is shown in each table.
The thickness of the foam sheet was measured by a thickness gauge.
The thickness of the foam sheet was adjusted by changing the casting conditions.

<<< Evaluation >>>
The appearance, the darkness of black, and the reflectance were evaluated for Examples, Comparative Examples, and Reference Examples. The evaluation results are shown in each table.

<< Appearance >>
The appearance of the foam sheet was visually observed and scored as follows.

◯: The cell is uniform and there are no cracks or voids on the surface △: The cell is slightly rough, but there are no cracks or voids on the surface ×: The cell is very rough and the cell is not formed (not foamed) ,
Or there are cracks or voids on the surface

<< Blackness >>
The L * value was measured using a color difference meter (CR-400 manufactured by Konica Minolta Japan Co., Ltd.) and scored as follows.

3 points: 20 or less 2 points: 20 or more 21 or less 1 point: 21 or more 22 or less 0 points: 22 or more

<< Reflectance >>
For the reflectance, measure the regular reflectance at an incident angle of 60 ° with an ultraviolet / visible spectrophotometer (UV-3100PC, Shimadzu Corporation) in the region of 300-800 nm, calculate the average reflectance, and calculate the average reflectance as follows. I gave a score.

3 points: 0.09 or less 2 points: 0.09 or more and 0.12 or less 1 point: 0.12 or more and 0.15 or less 0 points: 0.15 or more

<< Comprehensive judgment >>
〇: Appearance is 〇 or △, optical characteristics are 4 points or more ×: Appearance is × or optical characteristics are 3 points or less

Claims (6)

A reflection-suppressing foamed sheet obtained by foaming and curing an emulsion composition containing a resin component and a black colorant.
The black colorant contains a dye (A) and a pigment (B).
The solid content of the black colorant in the emulsion composition is 5 to 15% by mass.
A reflection-suppressing foamed sheet having a solid content ratio ((A) / (B)) of the dye (A) and the pigment (B) of 0.01 to 0.35. The antireflection foam sheet according to claim 1, wherein the density is 50 to 500 kg / m ³ . The antireflection foam sheet according to claim 1 or 2, wherein the blackness (L * value) is 22 or less. The dye (A) is a metal complex salt dye or an azo dye, and is
The antireflection foam sheet according to any one of claims 1 to 3, wherein the pigment (B) is carbon black having a particle size of 300 nm or less. The specular reflectance of 60 ° incident in light with a wavelength of 300 to 800 nm is 0.2% or less.
The antireflection foam sheet according to any one of claims 1 to 4, wherein the thickness is 80 to 1200 μm. The saturation indicated by the distance [√ (a * value ^ 2 + b * value ^ 2)] from the intersection of the a * value and b * value coordinates (a * value, b * value: 0,0) is 1.5 or less. The antireflection foam sheet according to any one of claims 1 to 5, wherein the antireflection foam sheet is characterized by the above.